Question

我正在创建一个程序，你需要使用bool函数来确定当用户输入时三个数字是否按升序排列。但是，bool函数始终评估为true。我错过了什么？这是我的代码：

#include <iostream>
#include <string>

using namespace std;

bool inOrder(int first, int second, int third)
{
    if ((first <= second) && (second <= third))
    {
        return true;
    }

    else
    {
        return false;
    }
}

int main()
{
    int first, second, third;

    cout << "You will be prompted to enter three numbers." << endl;
    cout << "Please enter your first number: ";
    cin >> first;
    cout << "Please enter your second number: ";
    cin >> second;
    cout << "Please enter your third and final number: ";
    cin >> third;
    cout << endl;

    inOrder(first, second, third);

    if (inOrder)
    {
        cout << "Your numbers were in ascending order!" << endl;
    }

    else
    {
        cout << "Your numbers were not in ascdending order." << endl;
    }

    return 0;
}

Answer 1

您需要实际调用该函数：

if (inOrder(first, second, third))

此

if (inOrder)

总是计算为true，因为它确实检查了函数指针是否为非空。

Answer 2

您必须存储函数的返回值，并测试它 - 或者直接测试函数。所以：

bool result = inOrder(first, second, third);

if (result)
{
(...)

或：

if (inOrder(first, second, third)
{
(...)

if(inOrder)始终评估为true的原因是它检查inOrder()函数的地址，该函数非零。

Answer 3

可能是你的意思

if (inOrder(first, second, third))

而不是

inOrder(first, second, third);

if (inOrder)

当你说if (inOrder)你实际上没有调用函数并检查结果时，而是使用变量inOrder作为条件，它只是指向函数入口点的指针，该函数总是计算为真。

Answer 4

试试这个：

bool b = inOrder(first, second, third);
if(b){.....}

您没有从inOrder函数

中获取结果

Answer 5

始终为true，因为您将函数的地址传递给if条件。由于该函数永远不会在地址0，因此条件始终为真。您需要存储函数的返回值：

bool ordered = inOrder(first, second, third);

或在if：

中调用该函数

if (inOrder(first, second, third))

Answer 6

这是工作副本。您需要存储函数调用中的o / p。

#include <iostream>
#include <string>

using namespace std;

bool inOrder(int first, int second, int third)
{
    if ((first <= second) && (second <= third))
    {
        return true;
    }

    else
    {
        return false;
    }
}

int main()
{
    int first, second, third;

    cout << "You will be prompted to enter three numbers." << endl;
    cout << "Please enter your first number: ";
    cin >> first;
    cout << "Please enter your second number: ";
    cin >> second;
    cout << "Please enter your third and final number: ";
    cin >> third;
    cout << endl;
    bool isordered;
    isordered = inOrder(first, second, third);

    if (isordered)
    {
        cout << "Your numbers were in ascending order!" << endl;
    }

    else
    {
        cout << "Your numbers were not in ascdending order." << endl;
    }

    return 0;
}

布尔总是评价为真

6 个答案: